Life and science at the Smithsonian Environmental Research Center

Ecology

...now browsing by category

Most animals are quite pragmatic in their gift-giving. When attracting mates, elaborate dance routines and ostentatious coloring certainly help. But when offering presents, males tend to give their significant others something they can actually use (unless they are sleazeballs—but more on that later).

Of course, what a female bush cricket finds enticing wouldn’t necessarily go over well for a chimpanzee, or an Arctic tern. What follows is a glimpse of romance in the rest of the animal kingdom. Below are four gifts animals can use to attract or care for their mates, and while they are usually thoughtful in context, we don’t recommend trying them at home.

Can’t get to water to fish up a blue crab? Want to teach about blue crabs and Smithsonian research but can’t make it to SERC or the Chesapeake Bay? Landlocked, but you want students to measure a crab’s carapace and learn about its life cycle? SERC has the answer: a virtual blue crab.

The blue crab is just part of the new Smithsonian X3D—a revolutionary way for visitors to interact with Smithsonian collections and research. In November 2013 the Smithsonian launched the Smithsonian X3D (beta) program, which allows visitors to flip, rotate and zoom in on digitized 3D images of objects from across the Institution. Right now they can explore more than 20 objects, including Amelia Earhart’s flight suit, the Wright brothers’ plane and a life mask of Lincoln.

Wood frogs (Lithobates sylvaticus) freeze solid over winter and come back to life in spring

by Karen McDonald

Wood frog (Dave Huth)

Here in North America there are a wide variety of toads and frogs, but perhaps none are so unusual as the wood frog. These frogs are found in Eastern North America, Canada, and up into Alaska. On a warm spring night you might hear them singing(click here for sound clip) near bogs, vernal pools or upland forests, but something remarkable happens to them this time of year in the winter: They freeze solid. Now freezing solid isn’t remarkable by itself, but what is remarkable is that the frogs will literally come back to life in the spring, after having no heartbeat or brain activity (they don’t even breathe) for up to eight weeks! This baffles and amazes scientists, who are actively studying them even now.

As mangrove trees lose ground to deforestation and urban sprawl, one development seems to be giving them a boost: climate change. Fewer winter cold snaps have empowered them to conquer new territory around their northern Florida boundary, according to a study of 28 years of satellite data from the Smithsonian Environmental Research Center and the University of Maryland.

An estimated 35 percent of the world’s mangroves have been destroyed since 1980, according to previous research, outstripping tropical rainforests and coral reefs. They are also some of the planet’s most valuable ecosystems. Mangroves protect coastal cities from floods and hurricanes. Their above-ground roots shelter many commercially valuable fisheries, including blue crabs, shrimp and lobsters. And they are phenomenal at burying carbon. The soils of coastal ecosystems like mangroves can store carbon at a rate 50 times higher than tropical rainforests. Scientists have estimated their total ecosystem services value more than $1.6 trillion a year—making the expansion a possible blessing.

“Some people may say this is a good thing, because of the tremendous threats that mangroves face,” said the study’s lead author, Kyle Cavanaugh, a postdoctoral research fellow at the Smithsonian Environmental Research Center in Edgewater, Md. “But this is not taking place in a vacuum. The mangroves are replacing salt marshes, which have important ecosystem functions and food webs of their own.”

It’s no surprise that invasive species can dramatically alter an ecosystem. Often, invasive species outcompete native species and disturb ecosystems that have not evolved to handle the new intruder(s). One such invader is the introduced common reed (Phragmites australis australis). Introduced Phragmites alters native plant communities that native animals use. Over the past several decades, native marshes containing plants such as marsh elder, saltmeadow hay, black needlerush, sea lavender, cordgrasses, threesquares and bulrushes have fallen to introduced Phragmites in the Chesapeake Bay and throughout the Atlantic coast, turning once diverse marshes into a thick monoculture forest.

It isn’t safe to eat the blue crabs from Berry’s Creek.American eels and white perch are also off-limits. White catfish are permissible, but only once a year, according to a New Jersey advisory for the Newark Bay Complex, where the creek is located. Crabbing in the 6.5-mile stream is illegal and can carry up to a $3000 fine. Waste from a now-defunct chemical processing plant, combined with more than a century of manufacturing, has made Berry’s Creek and its surrounding wetlands hot spots for mercury pollution.

The Environmental Protection Agency calls places like Berry’s Creek “Superfund sites”—a label for abandoned or neglected sites that became dumping grounds for hazardous waste. Some of the highest levels of mercury contamination in the U.S. exist in Superfund sites. Cynthia Gilmour knows this first-hand. As a microbial ecologist at the Smithsonian Environmental Research Center, she has worked in several. But short of digging up the polluted sediments and dumping them elsewhere (an expensive and ecologically risky proposition), not many methods exist to get rid of the problem.

“If we use the traditional technologies of removing that and putting it in a landfill, we don’t have a wetland anymore,” says Upal Ghosh, an environmental engineer from the University of Maryland, Baltimore County, who works with Gilmour.

This fall, Gilmour and Ghosh explored a new technique: using charcoal to trap it in the soil.

Have you ever wondered how far a fish can swim in one day? Acoustic telemetry enables researchers to track the movement, migration and behavior of fish. Beginning this past summer, the Fish and Invertebrate Ecology Lab started using acoustic telemetry to study the movement patterns of invasive blue catfish in the Patuxent River, a tributary of Chesapeake Bay.

Native to the Mississippi River, blue catfish were introduced for sport fishing in Virginia in the 1970s. Since introduction, these non-native top predators have expanded their range into many of Maryland’s tributaries. Their voracious appetites affect native fish populations and disrupt the food webs in these rivers. Blue catfish are the largest and most migratory species of catfish in North America. In their native waters, blue catfish have been known to migrate up to 200 km between different habitats used for spawning, feeding and overwintering. But little is known about their movement patterns within the Chesapeake Bay watershed, which is our motivation for using acoustic telemetry to track the movements of individual blue catfish.

Similar to radio tracking used to locate animals over vast distances, acoustic telemetry is a two-part system: Each fish has a transmitting tag, which emits a unique series of underwater sounds or “pings” at a random interval every one to three minutes. Stationary receivers then detect and decode these pings whenever a fish swims within range of the receiver. These detection data are converted to digital data and stored until researchers download the data onto a computer.

Interning at SERC for the past six months has given me the opportunity to be involved in every step of the process—some of which were messier than others.

The threat of disappearing coastlines has alerted many to the dangers of climate change. Wetlands in particular—with their ability to buffer coastal cities from floods and storms, and filter out pollution—offer protections that could be lost in the future. But, say co-authors Matt Kirwan and Patrick Megonigal, higher waters are not the key factor in wetland demise. Thanks to an intricate system of ecosystem feedbacks, wetlands are remarkably good at building up soil to outpace sea-level rise. But this ability has limits. The real issue, the scientists say, is that human structures such as dams and seawalls are disrupting the natural mechanisms that have allowed coastal marshes to survive rising seas since at least the end of the last ice age.

Researcher Mike Lehmann makes his way through dwarf-form mangroves in the Gulf of California. (C. Johnston)

As you approach stands of mangroves in Florida, you’re likely to notice a few things. They form expansive forests along protected seashore (usually in lagoons and estuaries) that often grow thick and tall overhead, providing welcome shade where the three species (black, white and red) intermingle. In the cool of their shade, they are clearly teeming with life; the constant pop of snapping shrimp ricochets around their oyster- and barnacle-encrusted roots while crabs and insects scurry along their branches.

These mangroves are different. There are no scurrying crabs or snapping shrimp or prominent rocks of oysters. Most of the insects have gone inside; their only traces are burrows and cocoons made in the safety of stems and rolled leaves. The blinding sun and gusty wind make it starkly obvious that the shady, protective canopy is only waist-high. The cactus on the rocky slope in the background gives it away: These mangroves are in Baja California, Mexico.

Herve Memiaghe, front, in Gabon’s Rabi forest plot. The red line marks where they measure the tree’s diameter. (Smithsonian Institution)

Herve Memiaghe isn’t the average intern. Before coming to the Smithsonian Environmental Research Center, the 33-year-old Gabonese ecologist had already earned a master’s degree and spent four years working at IRET, the Institute for Research in Tropical Ecology in Gabon. Since 2012 he has also done field work in the Rabi plot as part of the Smithsonian’s global forest study.

The 25-hectare Rabi plot sits on the southwest coast of Gabon. Diversity spikes in the rainforests of Central Africa, where a single hectare can contain more than 400 different species. And that’s just the trees. The animals bring problems of their own. In Memiaghe’s experience, it’s not uncommon for hungry elephants to eat the tree tags along with the leaves.

“Sometimes we find the tag in the dung of elephants,” Memiaghe says. Usually the scientists can figure out where the tag came from, so it doesn’t throw off their research that much. “It just maybe can be a mess for the new people.”